iOS NSDate日期加减

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];

[dateFormatter setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"UTC"]];

[dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm"];

日期加

        NSDate *Date0 = [datePicker date];

        NSTimeInterval interval = 60 * 60 * 2;

        NSString *titleString = [dateFormatter stringFromDate:[Date0 initWithTimeInterval:interval sinceDate:Date0]];      

日期减

         NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

         unsigned int unitFlags = NSHourCalendarUnit;//年、月、日、时、分、秒、周等等都可以

         NSDateComponents *comps = [gregorian components:unitFlags fromDate:Date1 toDate:Date2 options:0];

         int hours = [comps hour];//时间差